U.S. patent application Ser. No. 12/499,545, the disclosure of which is incorporated herein in entirety by reference, discloses a fuel system for an engine that controls the status of an output conduit or passage to open or close the outlet passage as a function of the relative pressure magnitudes of an inlet passage to the engine and atmospheric pressure. An actuator moves in response to this relative pressure condition in the inlet conduit to control the flow of fuel from a cavity of a fuel reservoir through an outlet passage of the fuel reservoir toward the inlet passage of the engine. As a result, fuel demanded by the engine is provided from the cavity of the fuel reservoir as needed while maintaining the sealed condition of the fuel reservoir when fuel is not demanded at the inlet passage of the engine.